when working on projects with large numbers of edits, it is tedious to build every crossfade by hand...

how 'bout this:

there's a project setting where we choose a global default fade type, then there's another project setting where auto-crossfade is toggled, then whenever we overlap two clips, a crossfade is auto-created if the auto-crossfade setting is "ON" for the project.

then we can go and tweak individual crossfades which need to be set up differently from the default.

to deal with moving clips during playback, i'd say it would be acceptable to disable crossfades on any clips involved with a current clip-move. then the crossfade becomes established when the clip stops moving.

not sure about the crossfade logic if a user overlaps more than two clips...